1. Create a webblock
2. check/edit the advanced properties for your own javascript/css
3. the html is place on the main window. if you want really down-to-earth html, use expression with the setting "escape content" set to "No"

and look into the richwidgets oml, really, it's the best tutorial you can have :)

You should import them by choosing "Import Image" from the Images folder right click menu, and the in then stylesheet use url(img/<ImageName>.<ImageExtension>). If this stylesheet is in a public web block that will be used in other eSpaces, you should use an absolute path insted of relative, like this: url(/<eSpaceName>/img/<ImageName>.<ImageExtension>)